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Published by the Oklahoma Water Resources Board in cooperation with the U.S. Geological Survey and Oklahoma Climatological Survey Page 1
Drought is Normal
Drought is a normal, recurrent aspect of Oklahoma’s climate. However, it causes extraordinary economic and social distress that can impact hundreds of thousands of people or more. Unlike floods, earthquakes, and other natural events, drought is a “creeping” phenomenon, which often lacks a well-defined beginning or end.
As shown in Figure 1, the onset of drought begins with a deficiency in rainfall, high temperatures and winds, and decreased humidity, collectively resulting in “meteorological” drought. As soil moisture is reduced, “agricultural” drought is experienced. If this scenario continues through several seasons, streamflow is reduced to critical levels and “hydrologic” drought results.
Oklahoma Historical Precipitation Trends
Measurement of statewide precipitation in Oklahoma from 1895 through 2011 indicates that 1) Oklahoma’s rainfall history is dominated by a decadal-scale cycle of relatively consistent alternating wet and dry periods lasting approximately 5 to 10 years; and 2) from the early 1980s through the first decade of the 2000s, the state experienced an extensive and unprecedented wet period, with the exception of the severe 2006 drought.
Some periods in Oklahoma history have been substantially drier than others, most notably the 1910s, 1930s, 1950s, and late 1960s. Between those drought periods, however, conditions have been generally wetter than average. The prolonged wet period of the 1980s and 1990s is unmatched by any period in the record (wet or dry) in terms of duration. This period is unique in its low variability, as almost all of the associated yearly totals fall within a fairly narrow window. The graph also suggests that the state may be experiencing the beginnings of yet another dry cycle.
Figure 1. Sequence of drought development.
A dust storm approaches a ranch near Boise City, Oklahoma, in 1935.
(AP Photo)
Resting along the way, a family flees the dust bowl region in the 1930s hoping for a new beginning in the west.
(Photographer, Arthur Rothstein, Library of Congress)

Published by the Oklahoma Water Resources Board in cooperation with the U.S. Geological Survey and Oklahoma Climatological Survey Page 1
Drought is Normal
Drought is a normal, recurrent aspect of Oklahoma’s climate. However, it causes extraordinary economic and social distress that can impact hundreds of thousands of people or more. Unlike floods, earthquakes, and other natural events, drought is a “creeping” phenomenon, which often lacks a well-defined beginning or end.
As shown in Figure 1, the onset of drought begins with a deficiency in rainfall, high temperatures and winds, and decreased humidity, collectively resulting in “meteorological” drought. As soil moisture is reduced, “agricultural” drought is experienced. If this scenario continues through several seasons, streamflow is reduced to critical levels and “hydrologic” drought results.
Oklahoma Historical Precipitation Trends
Measurement of statewide precipitation in Oklahoma from 1895 through 2011 indicates that 1) Oklahoma’s rainfall history is dominated by a decadal-scale cycle of relatively consistent alternating wet and dry periods lasting approximately 5 to 10 years; and 2) from the early 1980s through the first decade of the 2000s, the state experienced an extensive and unprecedented wet period, with the exception of the severe 2006 drought.
Some periods in Oklahoma history have been substantially drier than others, most notably the 1910s, 1930s, 1950s, and late 1960s. Between those drought periods, however, conditions have been generally wetter than average. The prolonged wet period of the 1980s and 1990s is unmatched by any period in the record (wet or dry) in terms of duration. This period is unique in its low variability, as almost all of the associated yearly totals fall within a fairly narrow window. The graph also suggests that the state may be experiencing the beginnings of yet another dry cycle.
Figure 1. Sequence of drought development.
A dust storm approaches a ranch near Boise City, Oklahoma, in 1935.
(AP Photo)
Resting along the way, a family flees the dust bowl region in the 1930s hoping for a new beginning in the west.
(Photographer, Arthur Rothstein, Library of Congress)